The present invention relates to an air spoiler device mounted on the tail or rear section of an automobile. More particularly, the present invention is concerned with an air spoiler device which reduces yawing moment acting on the automobile to ensure stable running of the automobile.
Air spoiler devices have been known which make positive use of stream of air along automobiles to ensure stability during running of the automobile. Hitherto, various types of air spoiler device have been known such as (1) those intended for reducing resistance of air or reducing lift acting on the body of the automobile, (2) those intended for preventing front or rear window from being dirty with dust or rain, and (3) those intended for ensuring high running stability against external forces such as that produced by a side or lateral wind, by means of, for example, vertical fins. These air spoiler devices are disclosed, for example, in Japanese Patent Examined Publication Nos. 57-51581 and 57-95266, as well as in Japanese Patent Unexamined Publication Nos. 60-161276 and 60-183252.
A side or lateral wind acting on an automobile cruising at a high speed, regardless of whether it is a rush wind or a steady wind, produces a lateral force and yawing moment, with the result that the running stability of the automobile is seriously impaired. The chance of high-speed cruising is increasing even for ordinary drivers, due to the current development of expressway networks.
The above-mentioned known air spoiler devices are mainly intended for reducing air flow resistance and/or the lift acting on the automobile or for preventing contamination of window glasses, and are not effective in improving running stability against a lateral wind. The air spoiler of the type (3) mentioned above produces a noticeable effect in the reduction of the yawing moment. However, this type of air spoiler device is still unsatisfactory insofar as it relies upon aerodynamic force acting on the vertical fins or the like. Namely, in order to obtain an appreciable effect with this type of air spoiler device, it is necessary that the size of the device be increased to such an extent that cannot be legally accepted.